The U.S. Pat. Nos. 7,798,736 and 7,922,207 each discloses a media binder arrangement having a cover with a front planar surface and a back planar surface connected by a spine planar surface. The spine planar surface includes several spine clamps each of which provides a closing force strong enough to hold a bundle of paper sheets. The clamps can be opened by a tension sheet attached to the spine clamp as well as to the cover of the media binder. When the cover is opened more than 270°, an opening force is transmitted to the spine clamps by the tension sheet. Each spine clamp is designed with planar side surfaces angled towards each other at the top of the spine clamp and connected to each other at the bottom by a planar clamp spine part. These patents also discloses that the media binders are provided with a datum spacer provided with a datum stop arranged perpendicular to and at one end of the datum spacer.
The U.S. Pat. No. 7,757,358 discloses sheet retention mechanisms for spring clamp binders having a spacer as a datum bar with a set of holes passing through the spacer and that each of the holes is aligned with holes in the spring clamp so that rivets or the like connects the spring clamp and the spacer. The spring clamps are provided with flat side surfaces which are closed at the top but can be opened against the spring force by a tension system.
In each of the previously known patents disadvantages occur in that they provide their tension sheet attached to the spring clamp by gluing, folding or riveting. These methods of attachments are time consuming and expensive.